Take note that all these herbs (aside from the ones you forage in the Thieves Forest) can't be gathered until you start the quest at Herman's.

A small dirty man with a straggly beard is bending over a steaming cauldron.
Herman the Hermit says "You've learned all about the aromatic plants. If you've got the stomach
and the nerve for it, I could do with some medicinal herbs, too. Do you want to help me?"
[Learn about Toxicology (20AP)]

Herman the Hermit gives you some basic training in handling dangerous plants.
Let's start with a Pink Spiny Seed Pod

You lose a Pink Spiny Seed Pod.
Herman the Hermit says "Thanks for fetching that herb - it was a Castor Bean Pod."
"Now you can get me a Red Hairy Vine."

You lose a Red Hairy Vine.
Herman the Hermit says "Thanks for fetching that herb - it was a Poison Ivy Stem."
"Now you can get me a Dark Blue Flower."

You lose a Dark Blue Flower.
Herman the Hermit says "Thanks for fetching that herb - it was a Aconite Flower."
"Now you can get me a Hard Smooth Nut-Shell."

You lose a Hard Smooth Nut-Shell.
Herman the Hermit says "Thanks for fetching that herb - it was a Wild Almond."
"Now you can get me a Handful of Small Red Berries."

You lose a Handful of Small Red Berries.
Herman the Hermit says "Thanks for fetching that herb - it was a Yew Berry."
"Now you can get me a Round Black Berry."

You lose 4 Round Black Berries.
Herman the Hermit says "Thanks for fetching that herb - it was a Belladonna Berry."
"Now you can get me a Violet Bell-Shaped Flower."

You lose 2 Violet Bell-Shaped Flowers.
Herman the Hermit says "Thanks for fetching that herb - it was a Foxglove."
"There doesn't seem to be any more that I can teach you right now."
You feel more alert.
You feel healthier.

You gain +10 Max AP and +10 Max HP.

You gain the ability to forage safely without poisoning yourself as you learn to identify each plant.
You don't have to wait till you've completed the quest for that benefit.